Comments

Either set up a partition on your HD or add another HD to your system and install the OS on that so that you have a boot-able drive and use that as your test bed for Carrara and other mission critical applications. If it works as expected, then maybe update your main HDs' OS, but make sure you have a backup. I like Carbon Copy Cloner if it still works for these later OS versions because it's free or donationware, as I recall, and it can make a boot-able copy of your disk.